The subject invention relates to a driveline and control assembly and method for continuously controlling driveline angles in a vehicle having an adjustable suspension system, such as an air-ride suspension system, during driving of the vehicle.
Heavy-duty trucks are used for hauling trailers and/or carrying heavy loads. These trucks may include a tandem axle assembly having a forward axle and a rear axle. A drive shaft extends between the forward axle and the rear axle to transmit output from the forward axle to the rear axle to more efficiently propel the truck. This drive shaft is commonly referred to as an inter-axle shaft. These trucks may also include adjustable suspension systems, such as an air-ride suspension system, to improve ride characteristics, such as riding comfort, of the truck. Adjustable suspension systems are also commonly used for adjusting a ride height of the truck. However, adjusting the ride height of the truck is frequently detrimental to driveline angles of the truck.
Driveline angles of the inter-axle shaft between the forward axle and the rear axle are compensated for at universal joints that rotate with the inter-axle shaft at ends of the inter-axle shaft. Thus, some drivelines have universal joints at both ends. A rotational velocity of the inter-axle shaft fluctuates with changes in the driveline angle of the shaft. There is an optimum set of driveline angles at the two ends. The driveline angles change when the ride height of the truck is adjusted and may vary between 0 and 11 degrees. At set-up of the vehicle, a chassis-to-axle dimension in the suspension system establishes driveline angles. The driveline angles are not verified (i.e., it is presumed that the angles are correct). However, sometimes the suspension systems can be improperly adjusted, or can become improperly adjusted. As a result, the driveline angles at the universal joints at the ends of the inter-axle shaft may become unbalanced. It is known in the art that when the driveline angles of the inter-axle shaft at each universal joint are unbalanced, the universal joints realize inconsistent rotational velocities causing the ends of the inter-axle shaft to rotationally accelerate and decelerate at different rates. This phenomenon induces increased noise, vibration, fatigue, and failure of the inter-axle shaft, the universal joints, and other components of a driveline of the truck.
Alternatively, it is also known in the art that when the driveline angles of the inter-axle shaft at each universal joint are balanced, then the effects of rotational acceleration and deceleration caused by the unbalanced driveline angles at each universal joint are cancelled out. That is, although the inter-axle shaft may be accelerating and decelerating, this effect is not transmitted to the forward and rear axles, and the noise, vibration, fatigue, and failure are minimized or eliminated.
It would be desirable to implement a control assembly and method for controlling driveline angles that monitors the rotational acceleration and deceleration on the drive shaft output or input, and continuously and automatically adjusts the suspension system of the truck to control the driveline angles relative to a drive shaft in response to any changes in rotational acceleration of the drive shaft.
A driveline and control assembly for a vehicle having an adjustable suspension system and a method for continuously and automatically controlling angles of a driveline of the vehicle are disclosed. The control assembly and method monitor rotational acceleration of a drive shaft of the vehicle and operate to reduce the magnitude of any acceleration on the drive shaft by adjusting the adjustable suspension. As a result, the control assembly and method control the driveline angles between the input and output of a drive shaft while an operator is driving the vehicle by automatically adjusting the adjustable suspension system at one end of the drive shaft to adjust the relative driveline angles at each end of the drive shaft to be more in balance. This reduces, or perhaps eliminates vibrations and other problems that result from unbalanced driveline angles.
More specifically, the adjustable suspension system is preferably an air-ride suspension system, and the drive shaft is an inter-axle shaft extending between a forward axle and rear axle. The inter-axle shaft is driven by output from the forward axle through a universal joint and transmits rotation to the rear axle through another universal joint. If the angles are not balanced then, a sinusoidal rotational velocity of the inter-axle shaft is produced. The sinusoidal rotational velocity defines alternating rotational acceleration and deceleration of the inter-axle shaft. The magnitude of acceleration and deceleration of the inter-axle shaft changes in relationship to the amount of imbalance in driveline angles of the inter-axle shaft. The control assembly and method of the subject invention determine any change in the rotational acceleration, or deceleration, of the inter-axle shaft, and inflates or deflates the air-ride suspension system to change the driveline angles and reduce acceleration by moving the angles to a more balanced relationship.
Accordingly, the subject invention provides a driveline and control assembly and method that senses the rotational velocity of the inter-axle shaft and determines differences in the rotational acceleration and deceleration of the inter-axle shaft so that the control assembly can automatically adjust the suspension system of the vehicle to reduce the magnitude of any acceleration on the inter-axle shaft. To accomplish this, the control assembly controls the suspension system to adjust and balance the driveline angles at the ends of the inter-axle shaft. As a result, excessive noise, vibration, fatigue, and failure of the inter-axle shaft is prevented. Damage to drivetrain components such as axle gearing, transmission gears, synchronizer pins, and clutch fatigue is also prevented.